Valve, preferably for anaesthetic plants of the closed type

ABSTRACT

A valve for anaesthetic plants of the closed type, in which a valve plate may move between an upper and lower valve seat. When the plate is in a mean position the anaesthetic mixture may ooze out from the pipe circuit and, when the plate bears against one of the seats the valve is closed. The plate is fixed to a spring and its movement is limited by an elastic member on the valve housing, said member being movable along the axis of the spindle on which the valve plate is fixed. The valve plate is arranged in a central channel which communicates with a ring-shaped chamber, this chamber communicating with an outlet. The valve may be used either for intermittent operation or for operation in such a way that it opens at a pre-determined pressure or for working when the patient is breathing spontaneously because the valve shall invariably allow a certain small surplus quantity to escape the system. Finally the valve ensures that any surplus anaesthetic mixture can be easily conducted to the floor.

United States Patent [191 Berner Dec. 25, 1973 VALVE, PREFERABLY FOR ANAESTHETIC PLANTS OF THE CLOSED TYPE [75] Inventor: Ole Berner, Herlev, Denmark [73] Assignee: Dameca A/S, Rodovre, Denmark [22] Filed: July 22, 1971 [21] Appl. No.: 165,308

[30] Foreign Application Priority Data July 27, 1970 Denmark 3887 [56] References Cited UNITED STATES PATENTS 2,623,725 12/1952 Sands ..l37/516.25

3,032,060 5/1962 Huffman .1 137/529 2,996,071 8/1961 Takaoka 137/63 R 3,575,196 4/1971 Marrese 137/312 282,090 7/1883 Kennish 417/540 Primary ExaminerRobert G. Nilson Assistant ExaminerEdward Look Attorney-Bucknam & Archer 57 ABSTRACT A valve for anaesthetic plants of the closed type, in which a valve plate may move between an upper and lower valve seat. When the plate is in a mean position the anaesthetic mixture may ooze out from the pipe circuit and, when the plate bears against one of the seats the valve is closed. The plate is fixed to a spring and its movement is limited by an elastic member on the valve housing, said member being movable along the axis of the spindle on which the valve plate is fixed. The valve plate is arranged in a central channel which communicates with a ring-shaped chamber, this chamber communicating with an outlet. The valve may be used either for intermittent operation or for operation in such a way that it opens at a predetermined pressure or for working when the patient is breathing spontaneously because the valve shall invariably allow a certain small surplus quantity to es- .cape the system. Finally the valve ensures that any 7 Claims, 14 Drawing Figures fATENTEnnEc25 197s 3.780.760

SHEET am 5 b33c! 21 40 1a PATENIEUDECZBIQB 3780.760

SHEET 5 UF 5 "I l 53 g 54 Fig. 77 Fig.72 Fig.73 Fig. 74

VALVE, PREFERABLY FOR ANAESTHETIC PLANTS OF THE CLOSED TYPE Anaesthetic systems of the closed type may consist of a pipe circuit into which the following parts are successively inserted: a first check valve, a valve of the type concerned, a rubber bag, another check valve, an anaesthetic mask, an absorber for absorbing the carbon dioxide of the expiration air, and finally a pipe connection for the supply of the anaesthetic means mixture hereinafter called anaesthetic mixture, which is positioned just before the first check valve.

When a patient is under an anaesthetic it may happen that his manner of respiration is altered, for instance because mucus has settled in his air passages or because he has altered his position. This alteration is reflected in a larger flow resistance against the gaseous anaesthetic mixture conducted to his lungs. The valve operator, who periodically compresses the rubber bag, will then feel a resistance against the compression of the bag.

In systems of the aforesaid kind the valve operator will then normally feel that the easiest way in which to establish a normal pressure in the pipe circuit is to increase the outlet opening of the valve positioned just before the rubber bag. However, this may cause difficulties because the valve operator then will press less anaesthetic mixture into the patient and this perhaps just at a time when the patient particularly needs it. In such cases it would be expedient if the valve operator could adjust the valve for intermittent operation so that the valve is open during expiration but next is closed during inspiration so that the patient will get the anaesthetic mixture under full pressure from the rubber bag. When the patient can again be normally ventilated, the valve may be readjusted for another manner of operation, i.e. in such a way that it only allows the anaesthetic mixture to escape from the circuit when a, predetermined pressure has been reached.

A valve is known to work intermittently and which has a bellows which can be lengthened and shortened depending on the pipe circuit pressure. The end of this bellows carries a plate, and this can via a lever affect a valve plate positioned over a valve opening beside the bellows. When the bellows is exposed to a little gas pressure such as it happens during the expiration, the bellows will not expand completely, and the valve plate will therefore not close. It will then be possible for part of the expiration air to ooze out of the circuit. If the valve operator applies a strong pressure on the anaesthetic mixture (air) in the circuit, the bellows will expand and the valve opening closes. This valve cannot work so that it normally is closed and only opens when exposed to a pre-determined pressure.

A valve is also known in which a spring-loaded valve plate covers a valve opening. The valve may well enough be adjusted to open at a definite pressure, but it cannot work intermittently.

The object of this invention is to produce a valve of the aforesaid kind which according to the manner in which the patient is to be ventilated and the skill of the valve operator can be used either for intermittent operation or for operation in such a way that it opens at a pre-determined pressure, or for operation when the patient is breathing spontaneously because the valve shall invariably allow a certain small surplus quantity to escape the system just at the valve ensures that any surplus anaesthetic mixture can be easily conducted downwards towards the floor.

The valve according to the invention is characteristic in that it has a valve member, preferably in the form of a valve plate, which can be moved between and brought to bear on against valve seats on an upper and lower portions which are provided with a centre channel. The valve is open for escape of the anaesthetic mixture from the pipe circuit of the plant when the plate is in a mean position, but closed when it bears on against one of the seats, and that the valve plate, controlled by a valve spindle connected with the carrying parts, is fixed to the upper carrying portion by means of a spring, only taking up a small space, preferably a spiral-shaped spring, and that the carrying parts are surrounded by a housing forming a mainly ring-shaped chamber communicating with the centre channel. This housing carries a flexible member, shiftable in the iongitudinal direction of the channel, and which can work together with the valve spindle so that adjustable, stopping means regulated by a spring are produced. The result achieved in the first place is that the valve can work intermittently. This happens when the flexible member, which can work together with the valve spindle, is shifted up so much that it goes free of the valve spindle. If just the pressure of the anaesthetic mixture is very low, the valve plate will rest against the lower seat, but if the pressure rises it will be raised so that a flow of anaesthetic mixture will escape past the plate and through the centre channel. If the pressure rises such as for instance when the valve operator presses the rubber bag strongly the plate will be brought to bear on against the upper valve seat whereby the valve and also the center channel is again closed. The anaesthetic mixture escaping through the centre channel will pass into the ring-shaped chamber and from there further away to the floor of the operating room. When the anaesthetic treatment is about to come to an end, one fails to supply anaesthetic means to the circuit, but supplies only oxygen. At the same time the flexible member is moved so far up against the centre channel that it forms an upper stop for the valve spindle and accordingly for the valve plate. The valve plate can in this case be moved from the lower valve seat and up to a position somewhat half between the valve seats. During the patients spontaneous respiration the valve functions in such a way that it closes during the inspiration so that the patient can only get air from the pipe circuit whereas during the patient's expiration the patients expiratory air flowing freely out from the circuit, and the anaesthetic means will then gradually ooze out with the expiratory air. The valve may also be adjusted in such a way that the anaesthetic mixture leaving the rubber bag has a pre-determined pressure. The flexible member is then turned so far downwards that the valve plate of the spindle is pressed firm against the lower valve seat. The fixing of the flexible member in this position determines the anaesthetic mixture pressure by which the valve plate is raised from the seat and the valve consequently opens.

An embodiment of the valve according to the invention is characterized in that the flexible member is constituted of a helical spring fixed internally in a movable top piece in the housing. The result is that the flexible member in a very simple way can be brought to bear against the valve spindle.

Further, according to the invention, the flexible member can on its underside have a stop arrangement for centering the upper part of the valve spindle which arrangement is primarily designed with a hollow plastic cone, the hollow side facing the spindle. In this manner the flexible member will not exert an oblique pressure on the spindle when it is pressed forward.

Besides, according to the invention, the top piece of the housing can be fixed on the cylindrical part of the housing by means of a thread so that it can be shifted in the axial direction of the housing when it is being turned at the same time. Hereby a simple design is obtained.

Further, according to the invention, the valve can have a downwardly directed outlet pipe connected with the housing and communicating with the ring-chamber. In this manner the anaesthetic mixture used is carried effectively downwards to strata of air near the floor of the operating room.

Moreover, according to the invention, the outlet pipe can have a short branch pipe ending in a pressure equalizing bag, and the outlet pipe may have a vacuum unit preferably of the type comprising a relatively thick pipe and an internal thin suction pipe so that around the suction pipe is formed a chamber for accumulation of anaesthetic mixture before this is sucked away through the suction pipe. The pressure equalizing bag will prevent the valve plate from undergoing rapid movements to and fro while the vacuum unit effectively will dispose of the anaesthetic mixture. If the suction from the vacuum unit becomes too powerful, it will be revealed by the pressure equalizing bag since: this will shrink. The pressure equalizing bag will thus also serve to control the working of the vacuum unit.

Further, according to the invention, the outlet pipe near the ring-chamber can be provided with a side opening, and to this opening can be attached a relatively small gas oscillation damping means the size of a fingerstall or a diaphragm of thin flexible material around the gas oscillation damping means, but up to the opening, a stiff protection dome may also be fitted. In this manner an effective dampening of the resonance oscillations which may occur in the valve when the patient is ventilated, the valve plate jumping on the seats, may be achieved.

According to the invention, the gas oscillation damping means may be connected with the opening in a way that it is arranged on a beaded pipe stub surrounding the opening, the open end of the flngerstall being for instance carried over the beaded stub. This ensures an effective fixing of the gas oscillation damping means. Moreover, according to the invention, the gas oscillation damping means may be of caoutchouc or plastic with a thickness of between 0,] and 1,0 mm. In this manner a high sensitivity of the gas oscillation damping means is achieved.

Further, according to the invention, the head can have a backward bent collar of an I- or L-shaped, projecting away from the symmetry axis of the opening. Thus it is easier to keep the gas oscillation damping means flrm on the bead in so far as the means has an O-ring along its edge the O-ring being kept in place by the collar.

Finally, according to the invention, the'protection dome may be transparent and fixed on the stub. Thus it is possible to control from outside at any time that the gas oscillation damping means functions correctly.

The invention is further explained below with reference to the drawing where FIG. I shows an anaesthetic system in which a valve according to the invention is inserted,

FIG. 2 is a side view of the valve according to the invention,

FIG. 3 is a front view of the same,

FIG. 4 the same seen from the bottom, the downwardly directed outlet pipe removed,

FIG. 5 is a cross section of the valve along the line 55 in FIG. 3, the top piece and the flexible member being raised so high that the valve can be used for intermittent working,

FIG. 6 represents the valve, the top piece turned so far down that the valve permits the patients spontaneous respiration,

FIG. 7 represents the valve, the top piece turned so far down that the flexible member with a certain prefixing presses the valve spindle and with this the valve plate so that the latter bears against the lower valve seat,

FIG. 8 presents the valve according to the invention shown in a small scale and provided with a pressure equalizing bag and a vacuum unit,

FIG. 9 represents shown in FIG. 2 provided with a gas oscillation damping means in the form of a fingerstall, which fingerstall is covered by a protection dome,

FIG. 10 a front view of part of the valve,

FIG. 11 shows the placing of the fingerstall and the protection dome shown in a somewhat larger scale and in longitudinal section,

FIG. 12 shows the pipe stub and bead around the opening shown in a large scale and in longitudinal section, the collar of the bead having cross section form of an I,

FIG. 13 illustrates the pipe stub and bead around the opening in a large scale, the collar of the bead having cross section form of an L, and

FIG. 14 illustrates a pipe stub and head around the opening viewed in a large scale and in longitudinal section, on which bead a diaphragm is placed.

The anaesthetic system shown in FIG. 1, which is of the closed type, consists of a pipe circuit comprising a check valve 1, valve 2 according to the invention, a rubber bag 3, another check valve 4, an anaesthetic mask 6, an absorber 8 and a pipe stub 9, through which fresh anaesthetic mixture can be supplied. When the system is in operation, it will, as explained above, be practical to adjust it for several forms of operation depending upon the respiratory way of the patient. The various forms of operation are conditional upon the valve 2 being arranged in a special way.

The valve 2 consists of a housing 10 on which is fitted a top piece 1 1 by means of a thread not shown. The top piece 11 will therefore be capable of an axial movement when it is at the same time turned. Through the housing is carried a pipe piece 13, and its ends are shaped in such a way that the pipe piece easily can be inserted in the pipe circuit in the place indicated by 2 in FIG. 1. FIG. 3 shows a front view of the valve. Inside the pipe 13 the lower end of the valve means proper are discernible. FIG. 4 shows the valve seen from below with, the downwardly directed outlet pipe removed. Through the opening 15 canbe seen the through-going pipe piece 13.

In FIG. 5-7 the valve according to FIG. 3 is seen in crosssection according to the section line S5. In a hole in the middle of the pipe piece 13 is fitted a lower carrying portion 16 which has a central hub part 16a. This part limits a part 17a of a central channel. In the hub portion 16a are fitted three radial carrying ribs 20. At their intersection point there is a hole through which the valve spindle 18 belonging to the valve plate 19 is carried. The upper end of the valve spindle 18 is controlled in the same way as its lower end and on top of the carrying position 16 is fitted an upper carrying position 21 with radial carrying ribs 22. At the intersection point of these ribs there is a guide hole for the upper portion of the spindle 18. The carrying part 21 limits a channel portion 17b. Between the carrying parts there is a valve chamber 25, and this makes up together with the channel parts 170 and 17b a central channel. The carrying 16 has a valve seat 26, and the carrying 21 has a valve seat 27. Inside the top piece a bushing 31 is fitted which at its lower end has an inwardly directed flange 32. Inside the bushing there is catch device 33 which is pressed downwards by means of a helical spring 34. The lower end of the catch device is coneshaped, its hollowness facing downwards the upper end of the spindle 18 so that the spindle easily can be drawn towards the central axis of the valve. The valve plate 19 is otherwise carried by a spiral spring 40 one end of which is fixed on the upper carrying part 21, and the lower portion of which is fixed on the upper side of the valve plate at its centre. Out of regard to the clearness of the figures, this spring is left out in FIG. 5 and 6, but appears however in FIG. 7.

Surrounding the carrying portion 16 and 21 but inside the housing 11 there is ring-chamber 36, and this communicates via the compartment under the top piece 11 with the central channel 17 FIG. 6. The ring-chamber communicates downwardly with the outlet pipe 12, the flow of the anaesthetic mixture however having to pass past the pipe portion 13, of FIG. 4.

The valve acts in the following way. When the anaesthetic mixture passes through the pipe portion 13 FIG. 5 on its way through the pipe circuit in FIG. 1, a small quantity of the anaesthetic mixture will pass out through the valve when this is open. It flows up through the channel section 170 and into the chamber 25 and from here further around the valve plate 19 and into the channel section 17b. In FIG. 5 the valve is closed, but when the valve plate 19 is lowered a few mm for instance because the pressure of the anaesthetic mixture is falling there will be a free passage to the channel part 17b. From here the anaesthetic mixture will then flow into the ring-chamber 36, and from there it flows then further downwards and past the pipe piece 13 and down into the outlet pipe 12. This pipe may be connected with a flexible rubber hose leading down to the floor of the operating room. The anaesthetic mixture oozed out, and since it is heavier than air it, will not very likely mix with the air surrounding the surgeons and nurses at the place where the plant is being used.

When the valve is required to work intermittently, the top piece 11 is screwed up so high that the lower end of the catch device 33 goes free of the upper end of the valve spindle 18 corresponding to the valve plate 19 bearing on against the upper valve seat 27. If there is no over-pressure in the anaesthetic mixture in the pipe piece 13, the valve plate 19 will bear on against the seat 26, but as soon as the patient emits a quantity of air, the pressure of the anaesthetic mixture in the pipe piece 13 will rise, and this will cause the valve plate 19 to lift from the seat 26. A small quantity of the anaesthetic mixture may now ooze out through the channel part 17a, the valve chamber 25, the channel part 17b, the ring-chamber 36, and the pipe piece 12. Immediately after, the valve operator operating the system concerned presses the rubber bag 3 FIG. 1 this will cause the anaesthetic mixture to flow partly to the right through the check valve 4 and partly backwards up to the pipe piece 13. During this phase the pressure will rise strongly, and the valve plate will then be pressed up against the seat 27 causing the valve to close. When now the valve operator presses the rubber bag 3 further together, a relatively high pressure will build up in the piping forward to the mask 6.

When one releases the rubber hose the pressure of the anaesthetic mixture will drop and immediately the valve plate 19 will move downwards affected by the spring 40. In the end it will bear on against the seat 26 when the working cycle will be repeated.

In FIG. 7 the valve is adjusted to open at a predetermined pressure in the anaesthetic mixture. The top piece 11 is here turned downwards to a position in which the spring-loaded catch device 33 through a certain pre-fixing force presses the valve spindle l8 and with it the valve plate 19 firm on against the lower seat 26. The pre-fixing force affecting the plate 19 is the sum of the elastic force of the spiral spring 34 and the elastic force of the coil spring 40. By turning the top piece 11 adequately down it is possible to cause the valve plate 19 to open only at an anaesthetic mixture pressure of say 10, 20, 30 or 40 cm water column. This is a considerably higher pressure than in the case of the intermittent operation where the the valve plate 19 lifts at an anaesthetic mixture pressure of app. 1.5 cm water column and is brought to bear on against the upper seat 27 at a pressure of app. 5 cm water column. When the valve is adjusted as in the case of FIG. 7, the valveoperator is certain that the patient is not ventilated at a pressure above the pressure at which the valve is adjusted. The valve acts also in this case as a sort of safety valve.

During the anaesthetic treatment the same anaesthetic mixture is circulating in the circuit shown in FIG. I, but as the patient absorbs some of the oxygen of the mixture, a suitable quantity of fresh oxygen must be supplied just as it is necessary to supply a suitable quantity of anaesthetic. This is done through the pipe stub 9, which for instance may be connected with an actually familiar rotary pump. The carbon dioxide emitted by the patient is absorbed by the actually familiar absorber 8. The reason why a continuous supply of a small quantity of fresh anaesthetic mixture is needed is that anaesthetic mixture oozes out through various leaks. The fresh anaesthetic mixture is supplied in a quantity which is larger than the quantity oozing out through the leaks, and the excess quantity occurring is let out through the valve. This discharge goes on during the intermittent function of the valve at the end of the expiration phase just as it goes on at the end of the inspiration phase when the valve is adjusted as shown in FIG. 7. When the anaesthesia is required to come to an end, one fails to supply fresh anaesthetic through the pipe stub 9 but carries on with the supply of oxygen. The concentration of the anaesthetic proper in the pipe circuit will hereby be reduced, and at a certain time'the patient will be able to respire spontaneously. The valve operator will then cease the periodic squeezing of the bag 3 and adjusts the valve in a sort of mean position shown in FIG. 6. The top piece 11 is here turned so far reach a higher place than a point about half-way between the two valves. Thus the valve plate has a limited possibility of movement. The patients expiration air will cause the valve plate to lift, and even if the pressure of this air should be large, the valve will not close since the plate, as stated above, cannot reach higher up than to a point half-way between theseats. Therefore, the valve will remain open during the better part of the respiration, and thus at each respiration on the part of the patient, a quantity of anaesthetic mixture will be drained off. The valve is perfectly closed by turning down the top piece 11 as far as is possible. The catch device 33 has over the cone-shaped portion a cylindrical elongation 33a, which under certain conditions can be brought to bear on against the inside of the top piece 11, ie when the top piece is turned down. In this case the catch device will be capable of immediately transferring the permanent pressure of the top piece to the valve spindle and with it to the valve plate 19 so that it bears firm on against the valve seat 26. The valve is now completely closed.

On the outer side of the housing an adjustment mark 41 may be cut FIG. 2 while on the outer side of the top piece several marks may be cut, of which one is indicated by 42. Each of the marks 42 corresponds to one of the ways of engagement mentioned above. When the valve is correctly adjusted a movable mark 42 is to be off the firm mark 41.

As shown in FIG. 8, the outlet pipe of the valve can be provided with a branch pipe 43, which is connected with a pressure equalizing bag 44. This prevents the valve plate, under certain unfavourable flow conditions, from vibrating to and fro between the seats 26 and 27 with a relatively high frequency. The pipe 12 may besides as shown in FIG. 8 be provided with a vacuum unit 45 consisting of a thick pipe 46 and a thin suction pipe 47 with a stub 48, by means of which stub the unit can be connected with a vacuum pump. Between the pipe 46 and the suction pipe 47 there is a space 49, which may serve for accumulation of the anaesthetic mixture. At the end of the pipe 46 connected with the outlet pipe 12, a perforated bushing (not shown) is fitted. Through the holes of the bushing the anaesthetic mixture can from the outlet pipe 12 penetrate into the chamber 44, the suction pipe 47 ending centrally in the bushing.

If the suction of the vacuum unit is too powerful this will immediately show in the shrinking of the pressure equalizing bag 44. Thus the form of this bag is also a good sign as to how the vacuum unit works.

In FIG.' 9 is seen how off an opening 52 also FIG. 11 in the outlet pipe 12 may be fitted a gas oscillation means 53in the form of a fingerstall of caoutchouc or plastic. Around the fingerstall there is a stiff protection dome 54. FIG. shows a front view of these parts. As it appears from FIG. 11, the finger-stall may at its opening have an O-ring 55 which is capable of working together with a collar 57 on a bead 58, which bead extends around the opening 52, coming from a stub 56. The protection dome 54 will normally be transparent so-that the oscillations of the fingerstall can be controlled from the outside. The protection dome is otherwise secured by means of an external thread on the stub 56 see FIG. 12. The oscillations taken up by the fingerstall are some quite feeble resonance oscillations which may arise in connection with the valve plate 19's bearing on against the valve seats 27, 26 see FIG. 5.

FIG. 12 shows more clearly how the bead 585 collar 57 has cross section form of an I. On the other hand, FIG. 13 shows a collar 60 having cross section form of an L. FIG. 14 shows the gas oscillation damping means designed as a simple diaphragm 61. This diaphragm, which is of elastic material, such as for instance caoutchiuc or plastic, has along its edge an O-ring 62, which is brought on to bear against the collar 57s backside. I

The invention may be altered in many ways without thereby deviating from its idea. Thus the bushing 31, the spiral spring 34 and the catch device 33, forming an elastic body, may be replaced by a solid, elastic bellows. The catch device shown in FIG. 5 may also be designed otherwise. For instance it may below have a cylindrical opening for control of the spindle 18.

The valve plate 19 need not just have the form of a plate. It may have any other form when it corresponds to the valve seats.

The embodiments described above of the valve according to the invention serve solely to illustrate the invention, not to limit the scope of protection.

I claim:

1. A valve for use in connection with a gas in anesthesia or in artificial respiration comprising a housing having a top member of adjustable level, support members within the housing, a valve plate mounted in said support members, said support members defining a channel for said gas which may be closed, two valve seats positioned one above and one under said valve plate in spaced relationship, a spindle in said housing movable in the vertical direction and connected with said valve plate, said top member being threadably engagable with said housing and upon being rotated being capable of moving in the axial direction, the level of said top member being adjustable to exert a predetermined pressure on said valve plate, first spring means in said top member capable of cooperating with said spindle second spring means connected with the uppermost of said support members and engagable with said valve plate, outlet means for the gas at the bottom of the housing, said valve plate being movable in the longitudinal direction and capable of engaging with one or the other valve seat and being capable of holding a position essentially midway between said two valve seats, said valve plate being in engagement with the upper seat, or being in said middle position or in engagement with said lower seat, the valve being completely closed when the valve plate engages with the lower seat, said valve being also closed when said plate engages the upper seat, said valve being open when the valve plate is not engaged with either of said two seats, means for rendering said top member free of the spindle whereby when the pressure of said gas is low, the valve plate engages with the lower seat, when the pressure of said gas increases said valve plate is pushed to said middle position, and part of said gas escapes, and said valve plate engages with the upper seat when the pressure of said gas is further increased, said first spring means being provided with stopping means forsaid spindle.

dampening the resonance oscillations resulting from the movement of said valve plate, said dampening means comprising a fingerstall, said side opening being provided with a bead member, said fingerstall having an O-ring engaging with said bead member, and a dome member around said fingerstall.

6. A valve according to claim 5 wherein said bead member has a collar of l-shaped cross section.

7. The valve according to claim 5 wherein said bead member has a collar of L-shaped cross section. 

1. A valve for use in connection with a gas in anesthesia or in artificial respiration comprising a housing having a top member of adjustable level, support members within the housing, a valve plate mounted in said support members, said support members defining a channel for said gas which may be closed, two valve seats positioned one above and one under said valve plate in spaced relationship, a spindle in said housing movable in the vertical direction and connected with said valve plate, said top member being threadably engagable with said housing and upon being rotated being capable of moving in the axial direction, the level of said top member being adjustable to exert a predetermined pressure on said valve plate, first spring means in said top member capable of cooperating with said spindle second spring means connected with the uppermost of said support members and engagable with said valve plate, outlet means for the gas at the bottom of the housing, said valve plate being movable in the longitudinal direction and capable of engaging with one or the other valve seat and being capable of holding a position essentially midway between said two valve seats, said valve plate being in engagement with the upper seat, or being in said middle position or in engagement with said lower seat, the valve being completely closed when the valve plate engages with the lower seat, said valve being also closed when said plate engages the upper seat, said valve being open when the valve plate is not engaged with either of said two seats, means for rendering said top member free of the spindle whereby when the pressure of said gas is low, the valve plate engages with the lower seat, when the pressure of said gas increases said valve plate is pushed to said middle position, and part of said gas escapes, and said valve plate engages with the upper seat when the pressure of said gas is further increased, said first spring means being provided with stopping means for said spindle.
 2. The valve according to claim 1 wherein said stopping means consist of a deformable conical shaped member being capable of engaging said spindle.
 3. The valve according to claim 1 wherein the outlet means is a pipe and which comprises pressure equalizing means connected to said pipe.
 4. The valve according to claim 3 comprising suction means connected to said outlet pipe for removal of said gas.
 5. The valve according to claim 1 which is provided with a side opening in the outlet pipe and means for dampening the resonance oscillations resulting from the movement of said valve plate, said dampening means comprising a fingerstall, said side opening being provided with a bead member, said fingerstall having an O-ring engaging with said bead member, and a dome member around said fingerstall.
 6. A valve according to claim 5 wherein said bead member has a collar of I-shaped cross section.
 7. The valve according to claim 5 wherein said bead member has a collar of L-shaped cross section. 